1. Field of the Invention
The present invention generally relates to a control system for auxiliary equipments for vehicles. More particularly, the invention relates to a control system for an auxiliary equipment for vehicles that is driven by engine power.
2. Description of Relevant Art
There are known varieties of control systems of the type which is to control, in conjunction with the accelerating condition of an engine, an auxiliary equipment for vehicles that is driven by the engine, such as a compressor of an air conditioner for cooling use.
Exemplarily, in Japanese Patent Publication No. 47-10721, published on Mar. 31, 1972, there is disclosed a control system which permits a part of engine power to be supplied to a compressor of an air conditioner for cooling use of a vehicle under either a condition that an acceleration pedal is depressed, exceeding a predetermined depressed quantity, or another condition that an intake pipe for a carburetor has a negative inner pressure attendant such as on a travelling of the vehicle on a downward slope.
For vehicles with such a control system, however, when operating the cooling-oriented air conditioner, which in general consumes much energy for operation, if the operating energy thereof is supplied from an engine that is limited in the capacity of energy output, the engine power available, as it is inherently intended, for propelling the vehicle is decreased by as much quantity as for the operation of the air conditioner, so that the capacity of acceleration is lowered.
For such a reason, there has since before been a demand that preferably, by detecting the accelerating condition of a vehicle, control should be made to stop the operation of the compressor, and there have already been proposed a variety of systems to realize such demand.
For example, in Japanese Utility Model Publication No. 51-41315, published on Oct. 7, 1976, there is disclosed a control system which, detecting the depressed quantity of an acceleration pedal and the number of revolutions per minute of an engine, controls a power distribution from the engine to a compressor for cooling use, so as to interrupt the distribution unless the engine revolution number is increased in accordance with the depressed pedal quantity.
In vehicles of the type which is equipped with an automatic transmission including a fluid coupling as a torque converter and furnished with a cooling-oriented air conditioner, the air conditioner generally has a compressor thereof driven with power sent from an engine through a mechanical power transmission route separated from a route to the automatic transmission, while the engine as a power source has nothing but a single crankshaft that outputs engine power available for both the compressor and the torque converter.
In this concern, driving energy given to the compressor is directly proportional to the revolution number of an input shaft of the compressor.
On the other hand, in the vicinity of a stalling point, the efficiency of power transmission of the fluid coupling is very bad and nearly equal to 0%, while in general the torque converter to be employed in an automatic transmission for vehicles has a relatively high revolution number at the stalling point, so that the energy to be consumed at the compressor when starting the vehicle is relatively large in comparison with the case of vehicles equipped with a manual transmission including no fluid coupling.
Therefore, in vehicles equipped with an automatic transmission including a fluid coupling as a torque converter, at the start, if a compressor of an air conditioner for cooling use has already been driven with power from an engine, the capacity of starting acceleration of the vehicle is all the more lowered when compared with the case of vehicles equipped with a manual transmission including no fluid coupling.
In other words, for vehicles equipped with an automatic transmission including a fluid coupling as a torque converter, the use of a cooling-oriented air conditioner accompanies a problem that the capacity of acceleration drops, particularly when starting the vehicle.
In such a case, therefore, it is first of all desired to accurately detect the state of starting acceleration of vehicle to thereby conduct shutdown control of a compressor and, besides, it would be preferred, as more rational if possible, to stop operation of the compressor, also when accelerating the vehicle to pass ahead, in accordance with the state of acceleration.
Most of the automatic transmissions as described are electronically controlled in view of the possibility of enlarging the freedom in setting operational characteristics as well as facilitations in securing the accuracy. Generally, the electronic control type automatic transmission includes a shift map developed on a coordinate plane with axes of abscissa and ordinate representing the velocity of a vehicle (hereinafter called "vehicle speed V") and exemplarily the degree of the opening of throttle valve (hereinafter called "throttle opening Th"), respectively.
The present invention has been achieved to successfully substantiate such desideratum as described in conjunction with conventional control systems for engine-driven auxiliary equipments such as air conditioners for cooling use for vehicles. Particularly, it is achieved with an eye to the fact that such desideratum is noticeable in those vehicles which includes an electronic control type automatic transmission having a fluid coupling as a torque converter, and that in general a shift map is utilized in the automatic transmission.